front brake master cylinder

[kirk]

I'm back again with a question about the front brake master cylinder on my 73 Honda CB 450-K.

Removing the cap on the master cylinder I found that the ?(bladder) inside the cylinder had dissolved and left a film of rubber which was attached to the entire inside area. If this material is removed with caution will the cylinder still function properly or will cleaning the inside with anything abrasive cause it to lose vacuum and not function?
The plastic seal is alright and the cap screws on easily but I am concerned about the seal.

Looking at a schematic it also appears there is quite an assembly for the piston moving the brake fluid along the line. Will age and lack of use cause a problem with this part of the brake assembly also?

Any information, thoughts are appreciated.

[tango911]

i wouldnt use an abrasive, but you can use some solutions that will break it down. maybe purple power mixed with a little water. u can use a 2000 or 3000 grit on the cylinder, shouldnt hurt it. buy a rebuild kit for the master and the caliper if need be.

[gr1976]

Are you going to rebuild the master cylinder anyway? Or just trying to clean it up?

[kirk]

I would prefer to clean it up. Getting a used unit doesn't guarantee it will work properly without the same type of repairs and new ones (if found) are expensive! If the master cylinder can be cleaned up it would seem a "rebuild" kit will (hopefully) provide a working front disk brake?

When the bike was put in storage the brake was working. I hope that the clean-up/rebuild will work to get things going again.

My next chore will be to determine if the air cleaners are OK or have dry-rot. The look and feel alright but may not work to allow enough air in? Anyone know how to check these?

Again, thanks for the help!!

[gr1976]

If the master cylinder moves free and doesn't leak you should be fine. Be careful of using chemicals to remove the rotted seal as they may attack the rubber seals on the piston. I'd just clean it with some scotchbrite pads or scrape with a razor.

As far as the air cleaner...I assume you mean air filter (in car speak the filter sits inside the cleaner....bikes its the airbox) ....they are usually pretty cheap if its been sitting a while I'd get a new one with a full tune up of the bike. However, if its not rotted or falling apart and you can see light through it ....it might be ok.

[kirk]

Thanks,

I appreciate all the information and suggestions. I'm sure it will next spring
before I have this bike going, but it should be worth it after doing all possible
work on my own. I guess that's 50% of the fun - or more!

Note: I had intended to just give it a general cleaning and tune-up and put
it on the road. The more I get into it the more I find myself taking everything apart
for easier cleaning and repair work. It should be an adventure.